AP Physics 1: Mechanics, Forces, and Energy Key Concepts

What comes before equations in physics?

Concepts

What does 'normal' mean in physics?

Perpendicular

What should you do when choosing a coordinate system for Newton's Laws?

Choose one axis so that SF = 0 in that direction.

What is the work done by a force if the force and direction are the same?

Always positive.

What is conserved in physics?

Mass and energy, linear momentum, angular momentum, electric charge.

What type of forces are present outside the nucleus?

Electromagnetic or gravitational.

What is the slope of a position-time graph?

Velocity (speed).

What does the slope of a velocity-time graph represent?

Acceleration.

What happens when acceleration and velocity are parallel?

The object speeds up.

What does the area under a velocity-time graph represent?

Displacement (change in position).

What happens to speed and acceleration as a falling object approaches terminal velocity?

Speed increases and acceleration decreases.

What is the only force acting on a projectile?

The projectile's weight (directed downwards).

How long does a ball take to hit the ground if rolled off a horizontal table compared to being dropped?

The same amount of time.

What is the relationship between tension in a rope and the weight of an object in equilibrium?

Tension equals the weight of the object.

What is the centripetal force in circular motion?

A net force towards the center.

What is the gravitational force inside a planet?

Varies directly with distance from the center.

What is the gravitational force outside a planet?

Varies inversely with the square of the distance from the center.

Where is a planet's gravitational field greatest?

At its surface.

How does a planet's gravitational field vary between the equator and the poles?

Less at the equator than at the poles due to rotation.

What is the tension in a string holding an object not always equal to?

The object's weight.

What is the direction of an object if the initial speed is zero?

The same as the direction of the unbalanced force.

What is the Law of Conservation of Momentum based on?

The action-reaction pair of forces in Newton's 3rd Law.

What happens to mechanical energy if only conservative forces are doing work?

It is conserved.

What is work done by kinetic friction?

Negative.

What is potential energy generally considered to be?

Assigned (arbitrary) energy due to position.

What is the work done in stopping an object equal to?

Its initial kinetic energy.

What is the work done in getting an object up to speed equal to?

Its final kinetic energy.

What is the relationship between work and kinetic energy in a before-after situation?

If there is a change in kinetic energy, work must have been done.

What is the definition of conservative fields?

Defined by potential energy functions.

What should you consider when asked for the kinetic energy of an object?

Use work-energy considerations if mass and speed are not obvious.